Referring to FIG. 1, a conventional readout system 9 is shown to include a sensing module 91, a converting circuit 92 and an ADC (analog to digital converter) 93.
The sensing module 91 senses an environmental parameter, such as acceleration, temperature, humidity, etc., and includes a variable capacitor (not shown). The variable capacitor may have a capacitance varying with a magnitude of the environmental parameter, such as a temperature magnitude, a humidity magnitude, a variation of acceleration, etc.
The converting circuit 92 detects the capacitance of the variable capacitor of the sensing module 91 and generates an analog voltage signal having an amplitude proportional to the capacitance.
The ADC 93 receives the analog voltage signal from the converting circuit 92 and converts the analog voltage signal into an output code.
However, in mass production, the capacitance of the variable capacitor of each of the aforementioned conventional readout systems 9 may be different due to process variation, and therefore the output codes provided by different conventional readout systems 9 may be different with the same environmental parameter. In addition, since users may not have demands to keep reading the output code when in a stable environment, continuous output of the output code may result in unnecessary power consumption.